Nisal Lahiru Ratnayake

Prediction and Measurement of Multiuser MIMO-OFDM Channel in Rural Australia

Commonwealth Scientific and Industrial Research Organisation (CSIRO) has recently conducted a technology demonstration of a novel fixed wireless broadband access system in rural Australia. The system is based on multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM). It demonstrated an uplink of six simultaneous users with distances ranging from 10 m to 8.5 km from a central tower, achieving 20 bits/s/Hz spectrum efficiency. This paper reports on the analysis of channel capacity and bit error probability simulation based on the measured MU-MIMO-OFDM channels obtained during the demonstration, and their comparison with the results based on channels simulated by a novel geometric optics based channel model suitable for MU-MIMO-OFDM in rural areas. Despite its simplicity, the model was found to predict channel capacity and bit error rate probability accurately for a typical MU-MIMO- OFDM deployment scenario.

Deterministic diffraction loss modelling for novel broadband communication in rural environments

This paper presents a deterministic modelling approach to predict diffraction loss for an innovative Multi-User-Single-Antenna (MUSA) MIMO technology, proposed for rural Australian environments. In order to calculate diffraction loss, six receivers have been considered around an access point in a selected rural environment. Generated terrain profiles for six receivers are presented in this paper. Simulation results using classical diffraction models and diffraction theory are also presented by accounting the rural Australian terrain data. Results show that in an area of 900 m by 900 m surrounding the receivers, path loss due to diffraction can range between 5 dB and 35 dB. Diffraction loss maps can contribute to determine the optimal location for receivers of MUSA-MIMO systems in rural areas.

Effects of user distribution on multiuser MIMO-OFDM channel capacity in rural area

Multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) is a promising technology to improve the spectrum efficiency of fixed wireless broadband access systems in rural areas. When MU-MIMO is deployed in predominantly line-of-sight (LoS) environments, for instance in rural areas, the problem of ill-conditioned channels may occur. This letter investigates the effects of capacity degradation with user distribution angle from 10° to full azimuthal angle, based on the results of a deterministic model. The deterministic model developed for rural MU-MIMO-OFDM has been validated with the experimental data. Furthermore, the validated deterministic model has been used to study the optimal distribution of users in a rural MU-MIMO-OFDM system. The optimum capacity has been observed for a user distribution with an angle between 180° and 360° around the access point.

Efficient wireless broadband communications for rural Australia

This paper discusses how internet services can be brought one step closer to the rural dispersed communities by improving wireless broadband communications in those areas. To accomplish this objective we describe the use of an innovative Multi-User-Single-Antenna for MIMO (MUSA-MIMO) technology using the spectrum currently allocated to analogue TV. MUSA-MIMO technology can be considered as a special case of MIMO technology, which is beneficial when provisioning reliable and high-speed communication channels. This paper describes channel modelling techniques to characterise the MUSA-MIMO system allowing an effective deployment of this technology. Particularly, it describes the development of a novel MUSA-MIMO channel model that takes into account temporal variations in the rural wireless environment. This can be considered as a novel approach tailor-maid to rural Australia for provisioning efficient wireless broadband communications.